Hitherto, there has been a refrigeration cycle apparatus configured to execute a refrigeration cycle through use of an “HFC refrigerant”, e.g., R410A that is non-combustible. R410A has an ozone depletion potential (hereinafter referred to as “ODP”) of zero and does not deplete the ozone layer unlike an “HCFC refrigerant”, e.g., R22. However, R410A has a property in which a global warming potential (hereinafter referred to as “GWP”) is high. Therefore, as one effort to prevent global warming, it is currently being considered to change the refrigerant that is used from an HFC refrigerant having a high GWP, e.g., R410A, to a refrigerant having a low GWP (hereinafter referred to as “low-GWP refrigerant”).
As a candidate for the low-GWP refrigerant, there has been an HFC refrigerant that does not have a carbon-carbon double bond in its composition. Examples of the HFC refrigerant include R32 (CH2F2; difluoromethane) having a GWP lower than that of R410A. Further, as a similar candidate refrigerant, there has been a halogenated hydrocarbon, which is one type of HFC refrigerant similar to R32 and has a carbon-carbon double bond in its composition. As such halogenated hydrocarbons, there have been known, for example, HFO-1234yf (CF3CF═CH2; tetrafluoropropene) and HFO-1234ze (CF3—CH═CHF). Here, in order to distinguish an HFC refrigerant having a carbon-carbon double bond in its composition from an HFC refrigerant that does not have a carbon-carbon double bond in its composition like R32, the HFC refrigerant having a carbon-carbon double bond in its composition is expressed as an “HFO refrigerant” in many cases through use of “O” standing for olefin (unsaturated hydrocarbon having a carbon-carbon double bond is called olefin).
Further, as a similar candidate refrigerant, similarly to HFO-1234yf, HFO-1234ze, and other refrigerants, there has been known HFO-1123 (CH2═CHF; 1,1,2-trifluoroethene (ethylene)) that is one kind of HFO refrigerant.
However, there is a possibility that HFO-1123, which is the low-GWP refrigerant, may cause self-decomposition. Therefore, in order to suppress the self-decomposition, an HFC refrigerant is mixed with HFO-1123 for use in some cases (see, for example, Patent Literature 1). According to Patent Literature 1, when HFO-1123 and an other refrigerant are mixed, a content ratio of HFO-1123 in a working fluid (100 mass %) is preferably 60% or greater, more preferably 70% or greater, further preferably 80%, and particularly preferably 100%.